In this JGT lesson, jazz guitarist Leon Rodriguez takes a unique look at ‘octaves’ in this music theory lesson specifically for guitarists.
We saw how two tetrachords laid out on a string set of one string defines the diatonic major scale in a really visible way. In the example, we see that the first note of the A tetrachord is one octave higher than the last note of the E tetrachord. The cycle of 4ths/5ths further present themselves! We associate symmetry of the fretboard with the symmetry of theory.
Stacking tetrachords further incorporates the symmetery of the theory with the symmetry of the fretboard which is the core of our mission. Abstractions are best accomplished from a solid vision of the concrete. Let the key of F illustrate fret range next. The major scale on a stringset of two compresses your fret range from 12 frets to 8 frets. It has the advantage of giving us 3 symmetrical string-pairs. Without populating the octaves with the chosen scale, the roots line up in a pattern of diagonal (green) lines that expose octaves in a stringset of three strings, further compressing the fret range to 3 and 4 frets along the even numbered strings. The adjacent C tetrachords in yellow are identical along the odd numbered strings.
We use identical fingering (1,1,3,4) for every single-string tetrachord so that we intuitively trust it and just focus on the first note of each tetrachord along a somewhat diagonal line of alternating 5ths and 4ths. Finger the left hand in a comfortable “one finger per fret” ergonomic. Tetrachords are common musical words in the language of scalewise (inside) movement. What’s important is that we create a fretboard vision of how theory presents itself to us via its own order. How you permutate that vision is well beyond this humble effort to illustrate that visons existence.
The decending ‘slide’ lines up best on the 3rd finger. Ascend and decend each tetrachord individually until intuitive.
Take another look at the octaves from the perspective of stringsets of three strings. We know that every octave has the potential to be populated by any scale, arpeggio or line. So moving octaves around is like carrying that potential around with you now that we have an acceptable fret range within our ‘one finger per fret’ suggested convention. These octaves are little boxes. 3 strings vertically by 3 frets horizonally. Play the following four measures. Four tetrachords merge into three major scales modulating across the cycle! Wow! The first tetrachord of the scale is the second terachord of the previous major scale in the cycle. The octaves on the 1st two bars are a 3 fret range, the 2nd two bars are a 4 fret range.
Leon Rodriguez began to study at 3 years old with an uncle, Jazz guitar with Chester Rupe as a teen, with Joel Sander, a prodigy of Jack Peterson and Classical with Javier Calderon, a prodigy of Andres Segovia at Del Mar College, now director of guitar at the University of Wisconsin, Jazz band at Corpus Christi State University, Texas State University, U.S Army Jazz Band and Jazz and Theory in NYC at the Sid Oliver School of Music in Manhattan. Leon regards himself a perpetual student of the instrument.
